1. Field of the Invention
The present invention relates to seals for heat exchangers. More particularly, the present invention relates to a mechanical tube seal system for a high temperature Air/Carbon Black laden process gas heat exchanger which utilizes a spring tensioned soft metal primary ring partially contained within a housing, the ring and housing together providing for sealing during expansion of the heat exchange tubes during the application of high heat to the tube during the process.
2. General Background
In the current state of the art, high temperature (HT) heat exchangers which are utilized in various industries require a very high cost of fabrication in order to provide for the expansion of the heat exchanger tubes during operation, yet continue to seal around the tubes. In the art, the individual heat exchange tubes provide for individual tube convoluted expansion joints which attribute to the high cost. Due to the rather complex fabrication involved, the heat exchange tube mechanisms result in a rather large, therefore rather expensive system, and in order to be properly supported, the support system must be quite extensive.
A typical heat exchanger would normally include a plurality of spaced apart, parallel tubes extending between opposing metal tube sheets. During the operation of the system, heat transfer would occur between the material inside the parallel tubes, and the material on the outside of the tubes, since in many applications, it would be disadvantageous to have the material on the inside of the tubes commingle with the material on the exterior. For this reason, it is imperative that there be a very tight seal between each of the tubes and the metal tube sheets. Furthermore, since the temperatures in the parallel tubes reach high levels, it is necessary to allow the tubes to undergo expansion and subsequent contraction without rupturing the mechanical seals between the parallel tubes and the tube sheets.
In the present state of the art, each of the tubes would be welded at a first end to one of the tube sheets and would be engaged to the second tube sheet with bellowed alloy steel convolutes which serve as expansion joints to allow the expansion and contraction of the tubes relative to the sheets. These so-called expansion joints are then welded to the tubes and the tube sheets. Although such conventional expansion joints are effective, they are relatively large in size, and increase the overall size and cost of the heat exchanger system. Furthermore, they tend to decrease the transfer efficiency of heat from the tubes.
Several patents were found in a search of the art which are pertinent to the present invention. These are cited in the accompanying prior art statement, being submitted herewith.